This invention relates generally to management techniques for a wireless communications network and, more particularly, to a system and method for providing wireless communications by merging packet service and mobile internet protocol.
There are many emerging trends in the communications world, including the increase in mobile network technology and the rise in packet data networks. There are many types of mobile network technology, including global systems mobile (xe2x80x9cGSMxe2x80x9d), code division multiple access (xe2x80x9cCDMAxe2x80x9d), time division multiple access (xe2x80x9cTDMAxe2x80x9d), and advanced mobile phone service (xe2x80x9cAMPSxe2x80x9d). Likewise, there are many types of packet data technology, such as asynchronous transfer mechanism (xe2x80x9cATMxe2x80x9d) and internet protocol (xe2x80x9cIPxe2x80x9d). A packet, or datagram, is a transmission method in which sections of a message are transmitted in scattered order and then re-ordered at a receiving node.
It is often desired to establish or maintain a connection that utilizes mobile network technology and packet data technology. For example, a global packet radio services (xe2x80x9cGPRSxe2x80x9d) technology is being developed to implement packet data technology for GSM networks. Separately, certain IP networks are being developed to support mobile, or wireless, communications (hereinafter referred to as xe2x80x9cmobile IPxe2x80x9d). Although the move to mobile IP technology is desirable, it has not merged well with conventional mobile technology.
GPRS
GPRS is an emerging GSM phase 2+ packet radio standard, similar to cellular digital packet data. It provides more efficient usage of the GSM radio interface because mobile units, or mobile nodes, can share a common radio channel. GPRS also provides direct interworking to the transmission control protocol IP (e.g. , the Internet), X.25 standard networks, and connectionless-mode network service networks for point-to-point services and point-to-multipoint services (e.g. , broadcast and group calls). GPRS supports concurrent operation with existing GSM services for circuit-switched speech, circuit-switched data and the service management system (xe2x80x9cSMSxe2x80x9d or xe2x80x9cthe intelligent networkxe2x80x9d) and is considered a long term replacement for signaling system 7 based SMS.
Consider for example FIG. 1a of the drawings. The reference numeral 10 refers, in general, to a simplified conventional GSM network that supports the GPRS standard, hereinafter referred to as a xe2x80x9cGPRS network.xe2x80x9d The GPRS network 10 allows a node such as a mobile node 12 to communicate with a packet network 14, such as the Internet, to further connect with a host 15. The host 15 is a correspondent node which may be either mobile or stationary. The GPRS network 10 also allows the mobile node 12 to communicate with a circuit switched network such as the public switched telephone network (xe2x80x9cPSTN,xe2x80x9d not shown). The mobile node 12 contains the necessary components to establish a wireless connection to a second/third generation (2G/3G) radio access network, represented by a base station 16. The base station 16 provides a voice link, a data link, and a control link to various nodes of the network 10.
For conventional wireless telephone calls, the base station 16 creates a voice and control link to a mobile switching center (xe2x80x9cMSCxe2x80x9d) 18, which provides a voice link to a telephone network such as the PSTN. The MSC 18 includes a visitor location register (xe2x80x9cVLRxe2x80x9d) 18a and is connected via a control link to other nodes such as a home location register (xe2x80x9cHLRxe2x80x9d) 20 and a SMS 22. The HLR 20 is enhanced to include GPRS subscription data for use in the GPRS elements discussed below. The SMS 22 may be a gateway MSC, for example, and may further link to other nodes, as well known in the art. The SMS 22, HLR 20, and MSC 18 are all interconnected via a mobile application protocol (xe2x80x9cMAPxe2x80x9d) interface.
For packet data calls, the network 10 includes several GPRS network elements, including GPRS support nodes (xe2x80x9cGSNsxe2x80x9d). A serving GSN (xe2x80x9cSGSNxe2x80x9d) 30 is connected to the base station 16 via a signaling and data transfer interface 32. The SGSN 30 is also connected to the MSC/VLR 18, 18a via a signaling interface 34, to the SMS 22 via a signaling and data transfer interface 36, and to the HLR 20 via a signaling interface 38. The SGSN 30 is further connected to a gateway GSN (xe2x80x9cGGSNxe2x80x9d) 40 via a signaling and data transfer interface 42 and to a GGSN 44 via a signaling and data transfer interface 46. The GGSN 40 is further connected to the packet network 14 via a signaling and data transfer interface 48 and the GGSN 44 is connected to a public land mobile network (xe2x80x9cPLMN,xe2x80x9d not shown).
Referring also to FIG. 1b, the SGSN 30 includes various modules to perform mobility management and authentication procedures. It also routes packet data as required. Like the VLR 18a, the SGSN 30 stores only a subset of subscriber data normally available at the HLR 20. For the sake of example, the SGSN 30 includes an originating call handler (or xe2x80x9cOCHxe2x80x9d) 50 and a terminating call handler (or xe2x80x9cTCHxe2x80x9d) 52. The OCH 50 handles exchanges with an originating agency while the TCH 52 handles exchanges with the terminating agency. Both the OCH 50 and the TCH 52 are configured to handle messages formatted in accordance with a predetermined industry standard GPRS protocol. It is understood that the OCH 50 and the TCH 52 are representative of various modules that perform messaging and other protocol functions.
The GGSNs 40, 44 provide functionality similar to a conventional gateway MSC, except that the GGSNs support packet data. The GGSNs 40, 44 use a packet data protocol which contains IP routing information. The routing information is used to xe2x80x9ctunnelxe2x80x9d data from the mobile node 12 to the current point of attachment. A tunnel is a path followed by a packet while it is encapsulated. While encapsulated, a packet is routed to a node where it is decapsulated and forwarded to its ultimate destination.
The GPRS elements 30, 40, and 44 are arranged according to xe2x80x9crouting areas,xe2x80x9d which are subsets of a GSM xe2x80x9clocation area.xe2x80x9d When a mobile node enters a routing area, it performs one or more registrations. There are three types of routing area registrations: 1) Routing Area Updating is when a mobile node enters a new routing area; 2) GPRS Attach/Detach indicates mobile node activation and prevents paging a mobile node when it is not active; and 3) Periodic Routing Area Update ensures that regular radio contact is maintained by the mobile node. Upon registration, the SGSN serving the new routing area updates the xe2x80x9ccontextxe2x80x9d of the mobile node. The context includes a GPRS Packet Data Protocol (xe2x80x9cPDPxe2x80x9d), which is part of the mobile node""s address. The PDP context is updated so that the GGSN in the old routing area will send packets to the new SGSN. Other parts of the context may include various identifiers, an access point name, and so forth.
Mobile IP
Mobile IP is an emerging xe2x80x9clayer 3xe2x80x9d type protocol that allows a mobile node to establish a wireless connection to an IP network. mobile IP essentially has three major subsystems. First, a discovery mechanism provides mobile nodes with new attachment points (new IP addresses) as they move within the IP network. Second, when the mobile node learns its new IP address, it registers it with its xe2x80x9chome network.xe2x80x9d A home network is a network, possibly virtual, that has a network prefix matching that of the mobile node""s xe2x80x9chome address.xe2x80x9d A home address is an IP address that is assigned for an extended period of time to a mobile node. It remains unchanged regardless of where the mobile node is attached. Standard IP routing mechanisms will deliver packets destined to a mobile node""s home address to the mobile node""s home network.
A third subsystem is that mobile IP allows data to be directed to the mobile node when it is away from its home network by using the registered IP address. For the sake of reference, mobile IP is discussed in greater detail in the book Charles E. Perkins, MOBILE IP: DESIGN PRINCIPLES AND PRACTICES (Computer and Engineering Publishing Group ISBN: 0-201-63469-4, 1998).
Consider for example FIG. 2 of the drawings. The reference numeral 100 refers, in general, to a simplified conventional mobile IP network. The network 100 allows the mobile node 12 to communicate with a packet network 104, such as a wireless local area network, to further connect with a host 105 or to the internet. The mobile node 12 includes the necessary components (not shown) to establish a wireless connection to a home agent 106a. A home agent is a router on the mobile node""s home network that maintains current location information for the mobile node and delivers packets to the mobile node when it is in away. Although the same mobile node 12 is described in FIGS. 1 and 2, it is understood that different equipment may actually be required for the different networks.
When away from its home network, the home agent provides a xe2x80x9ccare-of addressxe2x80x9d for the mobile node 12. A care-of address is a termination point of a tunnel toward a mobile node, for packets forwarded to the mobile node while it is away from home. There are two different types of care-of address: a foreign agent care-of-address is an address of a foreign agent with which the mobile node is registered, and a collocated care-of address is an externally obtained local address which the mobile node has associated with one of its own network interfaces. When the mobile node is away from home, it registers its care-of address with its home agent. The home agent 106a provides a data link and a control link to various nodes of the network 100. The mobile node uses its home address as the source address of all IP packets that it sends, except where otherwise required.
The mobile node 12 may roam about the mobile IP network 100 by establishing wireless (or wireline) connections with various foreign agents 106b, 106c. A foreign agent is a router in a xe2x80x9cvisitedxe2x80x9d foreign network which cooperates with the home agent to complete the delivery of packets to the mobile node while it is away from home. A visited foreign network is a network other than a mobile node""s home network, to which the mobile node is currently connected. The foreign agent maintains a visitor list of all the visiting mobile nodes. For the sake of example, the mobile node may roam to a location xe2x80x9cAxe2x80x9d and establish a wireless connection with foreign agent 106b in a first visited network, and then may roam to a location xe2x80x9cBxe2x80x9d and establish a wired connection with foreign agent 106c in a second visited network.
When the mobile node 12 is roaming (for instance, at position A), packets sent to the mobile node""s home address are intercepted by the home agent 106a, tunneled to the care-of address, received at the tunnel endpoint (foreign agent 10b), and finally delivered to the mobile node. In the reverse direction, packets sent by the mobile node 12 are generally delivered to their destination using standard IP routing mechanisms, not necessarily passing through the home agent 106a. 
Mobile IP has a process called xe2x80x9cIP Security.xe2x80x9d IP security is a tunneling security context between a pair of nodes. For example, IP Security may use a Security Parameters Index for identifying a security context between a pair of nodes among the contexts available in the mobility security association.
It is desired to merge wireless network packet service, such as is described in FIG. 1, with mobile IP service, such as is described in FIG. 2.
It is further desired that this merger be relatively simple to implement.
It is also desired that a mobile node may seamlessly roam between a wireless network and a mobile IP network.
In response to the problems and needs described above, provided is a network, system and method for merging a packet service such as GPRS with a mobile internet protocol. For example, a GPRS network may include a first base station for providing wireless access to a mobile node, a GPRS support node (GSN) connected to the base station, and a security gateway for connecting the GPRS network to a second network that may use the mobile internet protocol. In one embodiment, the GSN is capable of creating an internet protocol tunnel connecting it to the second network through the security gateway. The GSN is capable of handling mobile internet protocol specific messaging and also converts the wireless access to mobile internet protocol specific messaging.
In some embodiments, the GPRS network also includes a second base station for optionally providing wireless access to the mobile node. Therefore, the GSN handles the mobility of the mobile node from the first base station to the second base station as well as the interface to the second network.
In some embodiments, the GPRS network also includes a register, such as a home location register, connected without mobile internet protocol specific messaging. The GSN can further communicate with the register and can serve as a proxy to the register for the second network.
In some embodiments, the GPRS network allows the mobile node to roam to a routing area served by the GSN. In this embodiment, the GPRS network sends a mobile internet protocol message to an old node, such as a foreign agent, in the mobile internet protocol network. The mobile internet protocol message includes an indicator that a context for the mobile node is desired.
In some embodiments, the method of the present disclosure allows the mobile node to transition from a first routing area to a second routing area in various combinations of networks. The method detects that the mobile node is in the second routing area and sends a mobile internet protocol message from a node in the second routing area to a node in the first routing area. The mobile internet protocol message indicates to the node of the first routing area that any packets received thereafter are to be routed to the second routing area. The mobile internet protocol message may include an indicator to the first routing area that the context for the mobile node is requested. The context can then be received from the first routing area into the second routing area if the second routing area is responsive to the indicator.
In some embodiments, the network of the present disclosure includes the GSN in a first routing area capable of providing a wireless connection to the mobile node roaming from a second routing area. The GSN includes a protocol structure for detecting that the mobile node is in the first routing area and sending a mobile internet protocol message to a node in the second routing area. The message indicates to the node of the second routing area that any packets received thereafter are to be routed to the first routing area. The protocol structure also provides an indicator to the second routing area that the context for the mobile node is requested.
In some embodiments, the method can be used for updating the home location register in the GPRS network of activities by the mobile node in the second network. The method receives a first mobile internet protocol registration request by an agent of the second network serving the mobile node, sends a second mobile internet protocol registration request to the GSN, requesting that the GSN serve as a proxy, and sends a location message to the register from the GSN.
In some embodiments, the method also sends a first registration reply to the GSN after the location message has been received by the register. The method then sends a second registration reply to the agent after the first registration reply has been received by the GSN.
In some embodiments, the handover method detects that the mobile node is in the second routing area and before handover occurs, sends a message from a node in the second routing area to a node in the first routing area. The message indicates to the node of the first routing area that any packets received thereafter are to be temporarily held. The handover can then be performed and the method can then indicate to the node of the first routing area to forward the held packets to the second routing area. This indication may occur, in some embodiments, after a timeout.
In some embodiments, the method stops data loss when the mobile node performs a handover from an old serving area to a new serving area. In these embodiments, the method provides a new message to an access interface between the two areas. When the mobile node is about to enter the new serving area, the method sends a GPRS handover request message to a node of the old serving area. The handover request message indicates that the node of the old serving area is to hold any packets destined for the mobile node until the node is notified that the mobile node is in the new serving area.
An advantage achieved by the present disclosure is that wireless network packet service, such as is described in FIG. 1, is merged with mobile IP service, such as is described in FIG. 2.
Another advantage achieved by the present disclosure is that the merger be relatively simple to implement.
Yet another advantage achieved by the present disclosure is that a mobile node may seamlessly roam between a wireless network and a mobile IP network.